<template>
  <div class="goods">
    <!--侧边栏菜单-->
    <div class="menu-wrapper" ref="menuWrapper">
      <ul>
        <li v-for="(item, index) in goods" class="menu-item"
            :class="{'current': currentIndex===index}" @click="selectMenu(index, $event)">
          <span class="text">
            <span v-show="item.type>0" class="icon" :class="classMap[item.type]"></span>{{item.name}}
          </span>
        </li>
      </ul>
    </div>

    <!--商品列表页-->
    <div class="foods-wrapper" ref="foodsWrapper">
      <ul>
        <li v-for="item in goods" class="food-list food-list-hook">
          <h1 class="title">{{item.name}}</h1>
          <ul>
            <li v-for="food in item.foods" class="food-item border-1px" @click="selectFood(food,$event)">
              <div class="icon">
                <img width="57px" height="57px" :src="food.icon"/>
              </div>
              <div class="content">
                <h2 class="name">{{food.name}}</h2>
                <p class="desc">{{food.description}}</p>
                <div class="extra">
                  <span class="count">月售{{food.sellCount}}份</span>
                  <span>好评率{{food.rating?food.rating:0}}%</span>
                </div>
                <div class="price">
                  <span class="now">¥{{food.price}}</span><span v-show="food.oldPrice"
                                                                class="old">¥{{food.oldPrice}}</span>
                </div>
                <div class="cartcontrol-wrapper">
                  <cartcontrol :food="food" @cartAdd="cartAdd" @foodChange="getSelectedFoods"></cartcontrol>
                </div>
              </div>
            </li>
          </ul>
        </li>
      </ul>
    </div>

    <!--购物车-->
    <shopcart ref="shopCart" :delivery-price="seller.deliveryPrice" :min-price="seller.minPrice" :selectFoods="selectFoods"></shopcart>

    <!--商品详情页-->
    <food :food="selectedFood" ref="food" @foodChange="getSelectedFoods" @addGood="cartAdd"></food>
  </div>
</template>

<script type="text/ecmascript-6">
  import BScroll from 'better-scroll';
  import shopcart from 'components/shopcart/shopcart';
  import cartcontrol from 'components/cartcontrol/cartcontrol';
  import food from 'components/food/food';

  const ERR_OK = 0;
  //  const ERR_FAIL = 1;

  export default{
    props: {
      seller: {
        type: Object
      }
    },
    data() {
      return {
        goods: [],
        listHeight: [],
        scrollY: 0, // 记录当前滚动到的位置.
        selectFoods: [],
        selectedFood: {}
      };
    },
    computed: {
      currentIndex() {
        for (let i = 0; i < this.listHeight.length; i++) {
          let height1 = this.listHeight[i];
          let height2 = this.listHeight[i + 1];
          // 这里有点难理解,它的思路是当遍历到最后1个元素时,height2是undefined,
          // 在这儿之前,都是有值的,所以!height总是false, 那么接着判断 || 后面的
          // 条件,这个条件才是计算当前索引的算法.如果在滚到最后一个元素之前就拿到了
          // 那么return出去, 如果拿不到则到最后一个元素时!height2=true,直接返回
          // 最后1个元素的索引i.
          if (!height2 || (this.scrollY >= height1 && this.scrollY < height2)) {
            return i;
          }
        }
        return 0;
      }
    },
    created() {
      this.classMap = ['decrease', 'discount', 'special', 'invoice', 'guarantee'];
      this.$http.get('/api/goods').then(response => {
        response = response.body;
        if (response.errno === ERR_OK) {
          this.goods = response.goods;
          // 拿到数据后刷新DOM.异步请求后刷新界面经常使用,有点类似Android里View的invalidate()
          this.$nextTick(() => {
            // 添加滚动效果.
            this._initScroll();
            this._calculateHeight();
          });
        }
      });
    },
    methods: {
      selectMenu(index, event) {
        // 原生的点击事件没有_constructed属性,better-scroll的则为true,所以根据这个过滤掉原生的点击事件.
        if (!event._constructed) {
          return;
        }
        let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook');
        let el = foodList[index];
        this.foodsScroll.scrollToElement(el, 300); // 滚动到指定元素,并指定耗费事件.
      },
      _initScroll() {
        this.menuScroll = new BScroll(this.$refs.menuWrapper, {
          click: true // 表示可以动过移动端点击.
        });
        this.foodsScroll = new BScroll(this.$refs.foodsWrapper, {
          click: true,
          probeType: 3  // 这个参数表示不管是快速滚动还是缓慢滚动,都告诉我滚动的位置(监听)
        });
        this.foodsScroll.on('scroll', (pos) => {
          this.scrollY = Math.abs(Math.round(pos.y));
        });
      },
      _calculateHeight() {
        let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook');
        let height = 0;
        this.listHeight.push(height);
        for (let i = 0; i < foodList.length; i++) {
          let item = foodList[i];
          height += item.clientHeight;
          this.listHeight.push(height); // dom的clientHeight即dom的高度
        }
      },
      cartAdd(target) {
        // 体验优化，异步执行下落动画.
        this.$nextTick(() => {
          let shopCart = this.$refs.shopCart.drop(target);
        });
      },
      getSelectedFoods(food) {
        console.log(food);
        if (this.selectFoods.length === 0) {
          this.selectFoods.push(food);
          return;
        }
        let tempFood = null;
        this.selectFoods.forEach((selectFood) => {
          if (selectFood === food) {
            tempFood = selectFood;
            if (food.count > 0) {
              selectFood.count = food.count;
            } else {
              this.selectFoods.shift(selectFood);
            }
          }
        });
        if (tempFood === null) {
          this.selectFoods.push(food);
        }
      },
      selectFood(food, event) {
        if (!event._constructed) {
          return;
        }
        this.selectedFood = food;
        this.$refs.food.show();
      }
    },
    components: {
      shopcart,
      cartcontrol,
      food
    }
  };
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../common/stylus/mixin.styl"

  .goods
    display: flex
    position: absolute
    top: 174px
    bottom: 46px
    width: 100%
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          margin-top: -1px
          z-index: 10
          background: #fff
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
          &.decrease
            bg-image('decrease_3')
          &.discount
            bg-image('discount_3')
          &.guarantee
            bg-image('guarantee_3')
          &.invoice
            bg-image('invoice_3')
          &.special
            bg-image('special_3')
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>
